Denon AVR-X3600H AV Receiver Review

[waynel]

Hopefully someone can pursue the idea of physically disconnecting the amps to get the performance for the L/R in all channels. However, it would seem to be important that you need to know what your are doing, and that things like amps can be very dangerous. For the average person there would be no way to know if opening up the receiver and disconnecting the amps would be safe. Hopefully someone with the knowledge of such things can investigate it as it is really interesting if it could be possible to for example to physically disconnect the amps you want to externally amplify and get performance that is significanly better than the current AV7705 and AV8805 as well as other processors. I would certainly urge caution if you don't know what you are doing (such as myself).

From having designed amplifiers (at radio and microwave frequency) I've been thinking of the various reasons for the preamp performance degradation when the power amp is swinging to large amplitudes and came up with a few hypotheses:

1) Large power amp swings are causing problems with the power supply - the evidence is against this as Amir measured good SINAD when other channel amplifiers where putting out high power levels

2) Parasitic coupling from the PA back to the preamp - either capacitive (more likely) or magnetic.

3) A large swing stability issue changing the input impedance to the PA under high swings

4) Some protection circuit activating causing non-linearity in the preamp or the preamp loading

It may be possible to disconnect the amp stage but might not be too simple as there could be some protection circuit that will detect this as a problem and interfere with the functionality of the AVS overall.

OK, with that said, who is going to try?

 

[GXAlan]

It may be possible to disconnect the amp stage but might not be too simple as there could be some protection circuit that will detect this as a problem and interfere with the functionality of the AVS overall.

And don't forget my post about the Service Menu which lets you turn off the protections! =P

 

[petew]

Could be as simple as disconnecting one cable. In the case of disabling only the center channel, only a few of the conductors would need interruption. Of course a qualified technician would need to look over the schematics to find the correct cable and be sure both the preamp and power amp will operate without the connection in place.

 

[John Galt]

Actually if you use it as prepro only, you can set ECO on and it will get you very close, say half way there.

@peng Do you think that setting ECO to On would also help the performance of the X3500 when using outboard amps exclusively?

I don’t understand how pre-out distortion is an issue when onboard amps are limited to maybe 20-30 watts and pushing nothing except heat...and I also understand that it’s more complicated than this. I would love to convince Denon that a firmware update is in order to simply save energy if nothing else. Why would they force thousands of users to waste energy as heat when the onboard amps aren’t even connected to anything.

 

[John Galt]

Great point, I would add that they should do what they have done with the x8500H so that the user can select which channel to disconnect. Some people would want to have the center channel disconnected too but may want to use the surround and height channels for those speakers that may not be as far from their listening positions and/or as hard to drive. The switches (IC chips) and relays are already there, its just software, it may even be possible for them to offer a FW update, for $20, more or less.

May be ASR can start a petition?

I would pay more than $20 to be able to completely disable the onboard amps on my 3500 if it would improve the pre-out performance when pushing 2 channel music volumes to the max via outboard amps.

 

[Dj7675]

If you reduce the output to 1.4 volts, SINAD of the center channel improves to 97 dB whereas the Left goes up to 103 dB. This is at volume position 79.5 dB (above is at 82.5).

I missed a few posts somehow... and it was one of the most important ones. @amirm thanks for taking the time to measure a few more things like HDMI, SINAD @ 1.4V, and additional power measurements. Of all of the AVR/Pre Pro's, this wasn't the one I thought we be around 100 SINAD. In particular for the other channels to be @ 97 if kept at 1.4V (Under 80 on the master volume). While not state of the art compared to 2 channel DACs and amps, it is a pretty amazing performance and a great value. Hopefully we get another Denon in the 4xxx, 6xxx etc tested as well.

 

[GeorgeBynum]

Could be as simple as disconnecting one cable.

I'm an amateur sticking my nose in where it probably doesn't belong, but 50 years ago, designing audio amps for commercial 2-way transceivers taught me that no termination in intermediate stages frequently led to oscillation ... all too often out of the hearing, or even audio, range. Be wary.

 

[peng]

@peng Do you think that setting ECO to On would also help the performance of the X3500 when using outboard amps exclusively?

I don’t understand how pre-out distortion is an issue when onboard amps are limited to maybe 20-30 watts and pushing nothing except heat...and I also understand that it’s more complicated than this. I would love to convince Denon that a firmware update is in order to simply save energy if nothing else. Why would they force thousands of users to waste energy as heat when the onboard amps aren’t even connected to anything.

John, I think as someone suggested before, if ECO is on the power amps might just clip sooner. So assuming the pre-outs SINAD drops due to power amp clipping, you may be better off to leave ECO off just to play safe (in theory..) It would be great if Amir verify this simply by measuring with ECO on and off, then we'll know for sure. D+M suggested external amp users to leave ECO on, so either they are not worry about the pre-outs performance because it has no effects, or they think no one is going to notice the difference in SQ between 70 dB and 98 dB.

A good technician should be able to disconnect the internal power amps quite easily. The potential issue is, the protection algorithm may not like it, but I believe we can fool the algorithm and sensing circuit by inserting a resistor between the pre-out and the power amp input, instead of a total isolation via relay(s). That's not a DIY project unless you have a 3500 that is out of warranty and you have the necessary knowledge and skill.

In reality, the X3500H can drive your M2200 to its rated output and beyond and you'll never hear a difference. You only need about 1.5 V, at that level, the output will output very close to 200 W into 8 ohms or 400 W into 4 ohms. I highly doubt the AVR-X3500H's SINAD would drop lower than 82 dB at 1.5 V if at 1.4 V the center channel of the 3600 could still do 96 dB. Don't forget the 3500 has the same preamp/DAC as the 3600, identical!!

Think about this, 86 dB is 0.005%, D+M's THD+N spec for their flag ship prepro AV8805 is 0.008%, that is 81.9 dB. I did some comparison listening using the 3500 vs the A23+CA preamp, as I posted at AH before, I heard no difference but I did not try reference level.

 

[John Galt]

John, I think as someone suggested before, if ECO is on the power amps might just clip sooner. So assuming the pre-outs SINAD drops due to power amp clipping, you may be better off to leave ECO off just to play safe (in theory..) It would be great if Amir verify this simply by measuring with ECO on and off, then we'll know for sure. D+M suggested external amp users to leave ECO on, so either they are not worry about the pre-outs performance because it has no effects, or they think no one is going to notice the difference in SQ between 70 dB and 98 dB.

A good technician should be able to disconnect the internal power amps quite easily. The potential issue is, the protection algorithm may not like it, but I believe we can fool the algorithm and sensing circuit by inserting a resistor between the pre-out and the power amp input, instead of a total isolation via relay(s). That's not a DIY project unless you have a 3500 that is out of warranty and you have the necessary knowledge and skill.

In reality, the X3500H can drive your M2200 to its rated output and beyond and you'll never hear a difference. You only need about 1.5 V, at that level, the output will output very close to 200 W into 8 ohms or 400 W into 4 ohms. I highly doubt the AVR-X3500H's SINAD would drop lower than 82 dB at 1.5 V if at 1.4 V the center channel of the 3600 could still do 96 dB. Don't forget the 3500 has the same preamp/DAC as the 3600, identical!!

Think about this, 86 dB is 0.005%, D+M's THD+N spec for their flag ship prepro AV8805 is 0.008%, that is 81.9 dB. I did some comparison listening using the 3500 vs the A23+CA preamp, as I posted at AH before, I heard no difference but I did not try reference level.

@peng Thank you very much for your thoughtful response and analysis. I really appreciate the time you took to lay out the facts so clearly. With help from you and people like @KEW I think that I may have been able to build a system that punches above it’s weight class in regards to value.

People like you make this forum what it is.

I’ve been running with ECO On for a while after I heard of D+M‘s recommendation and I haven’t noticed any reduction in performance. I have to admit that I really love being able to push my system and the amps and receiver never get more than warm, and there’s not a fan anywhere in the mix. It kind of bothered me when I had ECO set to Auto and kept hearing the relays click when I barely raised the volume, and felt the receiver cabinet temperature increase...when I knew the receiver wasn’t really doing any more work and I was just wasting electricity and increasing the receiver temp.

 

[GXAlan]

Looking at the Service Manual for the X4500H, you should be able to pull out CN461 and CN462 connectors to remove the power from the amplifiers.

The two white connectors highlighted here. The service manual already provides info how to remove protection.

While holding down buttons "ZONE3 SOURCE", "STATUS" and "CURSOR 0" simultaneously, press the power button to turn on the power.

@amirm , have you already shipped the X3600H back?

 

[John Galt]

Looking at the Service Manual for the X4500H, you should be able to pull out CN461 and CN462 connectors to remove the power from the amplifiers.

The two white connectors highlighted here. The service manual already provides info how to remove protection.

While holding down buttons "ZONE3 SOURCE", "STATUS" and "CURSOR 0" simultaneously, press the power button to turn on the power.

@amirm , have you already shipped the X3600H back?

I know this is a 3600 thread, but this same issue is relevant to the 3500 as well. I’m half tempted to start unplugging cables at the direction of someone who has the experience and service manual.

I’m assuming that one could just hook up a voltmeter to the left or right channel and get a before and after voltage reading, after should be zero.

I’d also like to lobby D+M to add internal amp shutdown via firmware update (assuming hardware is already there) simply for environmental reasons. I think there are receivers burning electricity unnecessarily by not being able to disable these unused amps. Does anyone know the best way to submit product enhancement requests to D+M?

 

[doodlebro]

But there is one thing that is special about this AVR: if you set it to 11 channel mode which is more than the number of amplifier channels it has, it lets you disconnect the internal amplifier and route that to pre-out.

Is that for all channels or just the two that get bumped off?

 

[amirm]

Looking at the Service Manual for the X4500H, you should be able to pull out CN461 and CN462 connectors to remove the power from the amplifiers.

The two white connectors highlighted here. The service manual already provides info how to remove protection.

While holding down buttons "ZONE3 SOURCE", "STATUS" and "CURSOR 0" simultaneously, press the power button to turn on the power.

@amirm , have you already shipped the X3600H back?

I shipped it back.

 

[amirm]

Is that for all channels or just the two that get bumped off?

Just two.

 

[Sagnet]

I’ve been running with ECO On for a while after I heard of D+M‘s recommendation and I haven’t noticed any reduction in performance.

Why Eco On, and not Auto? With Auto, the AVR itself will decide when to cut back on the power, and when not to.

 

[John Galt]

Why Eco On, and not Auto? With Auto, the AVR itself will decide when to cut back on the power, and when not to.

D+M has recommended setting ECO to On for those using outboard amps exclusively, and I really don’t like hearing the relay clicking on and off when I change the volume level.

That said, if it’s ever proven that D+M is ‘wrong’ from a performance standpoint and there’s even a slight improvement in pre-amp output quality with ECO set to Auto of Off, I’ll reconsider.

 

[North_Sky]

It's nice to see a midrange Denon receiver that looks and measures svelte.
...And with the features to please a whole midrange bunch of customers.

Stay safe aim straight

 

[MX48]

Looking at the Service Manual for the X4500H, you should be able to pull out CN461 and CN462 connectors to remove the power from the amplifiers.

The two white connectors highlighted here. The service manual already provides info how to remove protection.

While holding down buttons "ZONE3 SOURCE", "STATUS" and "CURSOR 0" simultaneously, press the power button to turn on the power.

@amirm , have you already shipped the X3600H back?

I have an X5200W which I believe is the 2015 model. It is similar to the X3600H.
Disconnected the 2 connectors and did the power on procedure and everything is working. Power amps are off.
Whether or not I am getting better specs or not of course is unknown but I am going to use it like this anyway since I have all out board amps.
Also seems to be running cooler but I assume that is expected since the amps aren't running.

 

[John Galt]

I have an X5200W which I believe is the 2015 model. It is similar to the X3600H.
Disconnected the 2 connectors and did the power on procedure and everything is working. Power amps are off.
Whether or not I am getting better specs or not of course is unknown but I am going to use it like this anyway since I have all out board amps.
Also seems to be running cooler but I assume that is expected since the amps aren't running.

And we have a trailblazer here folks. Thanks for the report!

Did you run across any tamper evident seals that could possible cause a warranty issue for those still under warranty?

 

[MarcT]

I have an X5200W which I believe is the 2015 model. It is similar to the X3600H.
Disconnected the 2 connectors and did the power on procedure and everything is working. Power amps are off.
Whether or not I am getting better specs or not of course is unknown but I am going to use it like this anyway since I have all out board amps.
Also seems to be running cooler but I assume that is expected since the amps aren't running.

My 5200 drives my center and surround speakers, while a separate amp drives my front L/R. Are you saying that ALL the amps in your 5200 are off? I might be interested in disconnecting the amps that drive the front L/R, but I suspect it's not possible with the 5200.